[Dsg-halla_ecal] ECal controls update

[Donald Jones]

Hi Marc,
I have turned off the heaters and pointed the fan at the rear of the crystals to cool things off faster. I would like to get started on swapping out sensors ASAP and then move the system to the Hall tomorrow or Thursday.
I really love the current readout. I learned a lot about the system already. One thing I learned is that if you are underutilizing the supply current like we are, the upper end of the PID output is not useful. For example, each SM zone has only 4 heaters where we could actually service 13 heaters and still fall just under the 12.5A current limit. At maximum voltage we are only drawing about 4.2A or 34% of maximum. Because of this, the control voltage saturates at 3.4V on the SM zones and anything above this does nothing since maximum current for this number of heaters has been reached. When the control voltage drops below 3.4, the current starts to reduce proportionally again. When you are well below the setpoint temperature the control output gets set to 10V and then slowly drops over a half hour, but the current doesn't change until it goes below 3.4. It's not the way I would have designed it, but ok. I don't think the adjustment sensitivity should depend on the load. I would much rather have the output adjust voltage, but I guess current is the right thing if you are driving LEDs. It just shows me that we need to design the final system with zones drawing close to the maximum current capacity of the supplies in order to maximize our control sensitivity.

I have one more request if it's not too difficult. Can you add to the program the ability to disable the PID and simply set the output voltage to a given value? Once the system is close to equilibrium it becomes obvious what that voltage setpoint is, and it will allow us to eliminate any PID oscillations. We will be left with the usual +/- 1 degree ambient temperature variations, but those are small enough to not worry us.
-Don


Donald Jones
Hall A/C Staff Scientist
Jefferson Lab
Newport News, VA
________________________________
From: Dsg-halla_ecal <dsg-halla_ecal-bounces at jlab.org> on behalf of Marc Mcmullen via Dsg-halla_ecal <dsg-halla_ecal at jlab.org>
Sent: Tuesday, August 29, 2023 8:51 AM
To: dsg-halla_ecal at jlab.org <dsg-halla_ecal at jlab.org>
Subject: [Dsg-halla_ecal] ECal controls update

Hi,

DSG has completed the latest update for the ECal controls which includes the following improvements:


  *   Configuration file for the PID settings
  *   Current monitoring for each heater channel (5 channels)
                            [cid:c9d6dc7a-c489-4fef-94d4-88bea41c42fc]
  *   Current monitoring display for the GUI
[cid:9c825458-b050-4127-9112-41d0275cb3ad]

The software is currently running as a Real-Time application on the cRIO. Should the software stop running the Watchdog software will reboot it to a safe state, with all heaters off. But the setpoints and PID settings will return.

DSG will monitor the system until it is shutdown and moved to Hall A.








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